Spectrophotometer

Abstract

The spectrophotometer of the present invention measures a spectral reflectance of an object to be measured to thereby determine a color value of the object to be measured based on a color-matching function of an XYZ color system and the spectral reflectance. The spectrophotometer includes an irradiation unit configured to irradiate the object to be measured with light having a spectral intensity distribution in which a relative intensity at a wavelength at which the value of z reaches its peak in the color-matching function is equal to or greater than 0.5.

What is claimed is: 
     
       1. A spectrophotometer that measures a spectral reflectance of an object to be measured and determines a color value of the object to be measured based on a color-matching function of XYZ color system and the measured spectral reflectance, the spectrophotometer comprising:
 an irradiation unit configured to irradiate the object to be measured with light; 
 a spectroscope configured to disperse reflected light from the object to be measured; and 
 a signal processing unit, 
 wherein the irradiation unit irradiates light having a spectral intensity distribution in which a relative intensity at a wavelength at a value of z in the color-matching function of XYZ color system is equal to or greater than 0.5 relative to a peak of the spectral intensity in which the spectral intensity distribution irradiated from the irradiation unit is normalized, and 
 wherein the signal processing unit determines:
 the spectral reflectance of the object to be measured based on a signal of light dispersed by the spectroscope, 
 a tristimulus value based on the spectral reflectance and the color-matching function of the XYZ color system, and 
 the color value of the object to be measured based on the tristimulus value of the XYZ color system. 
 
 
     
     
       2. The spectrophotometer according to  claim 1 , wherein the relative intensity is 1. 
     
     
       3. The spectrophotometer according to  claim 1 , wherein the spectral intensity distribution of the irradiation unit has a peak at a wavelength within the range from 440 nm to 460 nm. 
     
     
       4. The spectrophotometer according to  claim 1 , wherein the color value of the object is a color value in the Lab color system. 
     
     
       5. A method of measuring a spectral reflectance of an object to be measured and determining a color value of the object to be measured based on a color-matching function of XYZ color system and the measured spectral reflectance, the method comprising:
 an irradiating step of the object to be measured with light; 
 a light receiving step of receiving light that reflected from the object to be measured and has been dispersed; and 
 a signal processing step of signal processing the received light, 
 wherein the irradiating step irradiates light having a spectral intensity distribution in which a relative intensity at a wavelength at a value of z in the color-matching function of XYZ color system is equal to or greater than 0.5 relative to a peak of the spectral intensity in which the spectral intensity distribution irradiated from the irradiation unit is normalized, and 
 wherein the signal processing step determines:
 the spectral reflectance of the object to be measured based on a signal of light dispersed by the spectroscope, 
 a tristimulus value based on the spectral reflectance and the color-matching function of the XYZ color system, and 
 the color value of the object to be measured based on the tristimulus value of the XYZ color system. 
 
 
     
     
       6. The method according to  claim 5 , wherein the relative intensity is 1. 
     
     
       7. The method for measuring according to  claim 5 , wherein the spectral intensity distribution of the irradiation unit has a peak at a wavelength within the range from 440 nm to 460 nm. 
     
     
       8. The method according to  claim 5 , wherein the color value of the object is a color value in the Lab color system.